As one of related arts concerning light interception, Patent Document 1 has disclosed an art for detecting the direction of the sun using an optical sensor and intercepting sunlight, which propagates in the direction, using a sun visor. To be more specific, the art provides an electronic sun visor system including a solar position measuring instrument, a sun visor, and a control circuit. The solar position measuring instrument uses a sunlight angle-of-incidence sensor to detect the angles of the sun in the horizontal and vertical directions with respect to the vehicle. The sunlight angle-of-incidence sensor, which is fixed to the back of an inside rearview mirror in a vehicle, includes (i) multiple slits having angles that are sequentially varied at several steps in vertical and horizontal directions and (ii) multiple photoelectric converters (or optical sensors) disposed at the bottoms of the respective slits. The sun visor has an appropriate number of interceptive members, of which transmission and interception can be electrically controlled, juxtaposed lengthwise and broadwise. The control circuit selects any of the interceptive members included in the sun visor according to an output of the solar position measuring instrument and instructs the selected interceptive member to intercept light.
The related art described in the Patent Document 1 poses a problem in that the shape of the interceptive members is, as described later, so improper that part of a driver's field of view is also intercepted.
As a solution of the problem underlying the related art described in the Patent Document 1, Patent Document 2 has disclosed an antidazzle apparatus for vehicles that controls interceptive members included in a sun visor by utilizing the ability of a route guide system for vehicles so as to intercept sunlight alone.
The antidazzle apparatus for vehicles described in the Patent Document 2 includes: a sun visor that can form an interceptive portion having a predetermined shape through electrical control; and a route guide system that is mounted as a navigation system in a vehicle to inform an optimal driving route according to entered conditions. The route guide system searches in advance a traffic signal located at an intersection existing in the driving route, and also searches an intersection, of which traffic signal is hard to see because of dazzling sunlight, on the basis of the positional relationship of the vehicle relative to the sun. The route guide system supplies a control signal to form an interceptive portion, which is shaped to hide the sun and makes it possible to see the traffic signal, in the sun visor at a time point before the vehicle approaches the intersection of the traffic signal.
As for other related arts, Patent Document 3 has disclosed an art for controlling a sun visor according to an eyepoint, and Patent Document 4 has disclosed an art for producing a control signal that defines an interceptive area in a shield on the basis of the deduced position of the sun and the position of a region concerned. Patent Document 5 has disclosed an art using a circular sheet interceptor, and Patent Document 6 has disclosed an art for detecting a driver's eye.                Patent Document 1: JP-S62-43923 U        Patent Document 2: JP-3518002 B2        Patent Document 3: JP-H10-016555 A        Patent Document 4: JP-2005-008058 A        Patent Document 5: JP-2004-314900 A        Patent Document 6: JP-2005-024313 A        
An unsolved problem underlies the antidazzle apparatus for vehicles disclosed in the Patent Document 2. Specifically, although sunlight can be intercepted so that the indication of a traffic signal can be discerned, a traffic sign, a guide plate, other vehicles, and pedestrians other than the traffic signal may also be intercepted.
Moreover, the related arts described in the other patent documents cannot hide sunlight alone because the number of interceptive portions formed in a sun visor is one. For example, when the position of the indicator portion of a traffic signal relative to a driver lies in the same direction as the position of the sun does, and when an attempt is made to hide the sun, the indicator portion of the traffic signal, a traffic sign, an intersection name indicator, and pedestrians are all hidden.